1. Field of the Invention
The present invention relates to a manufacturing method of a corrugated tube and an apparatus therefore.
2. Description of Related Art
Japanese Utility Model Publication No. SHO 63-85319 discloses a manufacturing method of a corrugated tube which comprises steps of: (a) chucking a relatively short tube at opposite ends of the tube, (b) heating the tube locally in a longitudinal direction of the tube to soften a portion of the tube, (c) imposing an axial load on the tube from opposite ends of the tube to bulge the heated portion, (d) then moving the tube forward by a predetermined distance, and (e) repeating the above (a) to (d) steps to continuously manufacture a corrugated tube.
If the above-described method is applied to a long tube to manufacture a long corrugated tube, the distance between the chucks at opposite ends of the tube is large. As a result, the tube tends to buckle or bow when axially pressed. Thus, the quality of the corrugated tube will be low. Further, because in the conventional method the pressing step and the forwarding step are in series with each other, the manufacturing time period of a corrugated tube is relatively long.